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1. Asynchronous carbon sink saturation in African and Amazonian tropical forests

Author

Gabriela Lopez-Gonzalez, David A. Coomes, Connie J. Clark, Hannsjörg Wöll, Douglas Sheil, Kofi Affum-Baffoe, Geertje M. F. van der Heijden, Katharine Abernethy, Hans Verbeeck, John Tshibamba Mukendi, Ted R. Feldpausch, Terese B. Hart, Sam Moore, Robert Bitariho, Francesco Rovero, Joey Talbot, Lise Zemagho, C. Amani, Jefferson S. Hall, Sean C. Thomas, Amy C. Bennett, Pascal Boeckx, Aida Cuni-Sanchez, Armandu K. Daniels, Fabrice Bénédet, Yadvinder Malhi, Alusine Fofanah, John R. Poulsen, David Kenfack, Lindsay F. Banin, Janvier Lisingo, Hans Beeckman, Jean-Louis Doucet, Eric Chezeaux, Emanuel Gloor, Mireille Breuer-Ndoundou Hockemba, Timothy R. Baker, Jan Reitsma, Vincent P. Medjibe, Christelle Gonmadje, Axel Dalberg Poulsen, Marie Noel Djuikouo Kamdem, Fidèle Baya, Serge K. Begne, Patrick Boundja, Adriane Esquivel-Muelbert, Lucas Ojo, Roel J. W. Brienen, Hermann Taedoumg, Natacha Nssi Bengone, Benjamin Toirambe, Lan Qie, Jon C. Lovett, Greta C. Dargie, Elizabeth Kearsley, Darlington Tuagben, George B. Chuyong, Sylvie Gourlet-Fleury, Fidèle Evouna Ondo, Terry Brncic, Pantaleo K. T. Munishi, Martin J. P. Sullivan, Tommaso Jucker, Simon Willcock, Yannick Enock Bocko, Emanuel H. Martin, Vianet Mihindou, Kelvin S.-H. Peh, Kathryn J. Jeffery, Simon L. Lewis, Emmanuel Kasongo Yakusu, Jean-Remy Makana, Andrew R. Marshall, Martin Gilpin, Bonaventure Sonké, Jeremy A. Lindsell, Faustin M. Mbayu, Corneille E. N. Ewango, Wannes Hubau, Suspense Averti Ifo, Peter M. Umunay, Duncan W. Thomas, Edward T. A. Mitchard, Ernest G. Foli, Lee J. T. White, Jaccques M. Mukinzi, Georgia Pickavance, James Taplin, Terry Sunderland, Annette Hladik, Stephen Adu-Bredu, Jason Vleminckx, Oliver L. Phillips, Sophie Fauset, Alexander K. Koch, David Harris, Miguel E. Leal, Alan Hamilton, Aurora Levesley, Michael D. Swaine, James A. Comiskey, Thalès de Haulleville, John T. Woods, David Taylor, Jim Martin, and Murray Collins

Subjects
0106 biological sciences, Carbon Sequestration, 010504 meteorology & atmospheric sciences, Rainforest, Carbon sequestration, Forests, Atmospheric sciences, 010603 evolutionary biology, 01 natural sciences, History, 21st Century, Sink (geography), Trees, chemistry.chemical_compound, Forest ecology, Tropical climate, Life Science, Biomass, 0105 earth and related environmental sciences, Carbon dioxide in Earth's atmosphere, geography, Tropical Climate, Multidisciplinary, geography.geographical_feature_category, Atmosphere, Temperature, Carbon sink, Carbon Dioxide, History, 20th Century, Models, Theoretical, Droughts, chemistry, Carbon dioxide, Africa, Environmental science, C180 Ecology, Brazil
Abstract

Structurally intact tropical forests sequestered about half of the global terrestrial carbon uptake over the 1990s and early 2000s, removing about 15 per cent of anthropogenic carbon dioxide emissions1,2,3. Climate-driven vegetation models typically predict that this tropical forest ‘carbon sink’ will continue for decades4,5. Here we assess trends in the carbon sink using 244 structurally intact African tropical forests spanning 11 countries, compare them with 321 published plots from Amazonia and investigate the underlying drivers of the trends. The carbon sink in live aboveground biomass in intact African tropical forests has been stable for the three decades to 2015, at 0.66 tonnes of carbon per hectare per year (95 per cent confidence interval 0.53–0.79), in contrast to the long-term decline in Amazonian forests6. Therefore the carbon sink responses of Earth’s two largest expanses of tropical forest have diverged. The difference is largely driven by carbon losses from tree mortality, with no detectable multi-decadal trend in Africa and a long-term increase in Amazonia. Both continents show increasing tree growth, consistent with the expected net effect of rising atmospheric carbon dioxide and air temperature7,8,9. Despite the past stability of the African carbon sink, our most intensively monitored plots suggest a post-2010 increase in carbon losses, delayed compared to Amazonia, indicating asynchronous carbon sink saturation on the two continents. A statistical model including carbon dioxide, temperature, drought and forest dynamics accounts for the observed trends and indicates a long-term future decline in the African sink, whereas the Amazonian sink continues to weaken rapidly. Overall, the uptake of carbon into Earth’s intact tropical forests peaked in the 1990s. Given that the global terrestrial carbon sink is increasing in size, independent observations indicating greater recent carbon uptake into the Northern Hemisphere landmass10 reinforce our conclusion that the intact tropical forest carbon sink has already peaked. This saturation and ongoing decline of the tropical forest carbon sink has consequences for policies intended to stabilize Earth’s climate.

Published
2019

2. The persistence of carbon in the African forest understory

Author

Benjamin Toirambe, Emmanuel Kasongo Yakusu, John Tshibamba Mukendi, Timothy R. Baker, Jan Van den Bulcke, Jean-Louis Doucet, Georgia Pickavance, Sofie Dierickx, Camille Couralet, Tom De Mil, Bhely Angoboy Ilondea, Peter M. Umunay, Joris Van Acker, David Harris, Jefferson S. Hall, James A. Comiskey, Jason Vleminckx, Sam Moore, Jan Reitsma, Aida Cuni-Sanchez, Joey Talbot, Lise Zemagho, Lindsay F. Banin, Lee J. T. White, John R. Poulsen, Murray Collins, Hans Beeckman, Victor Deklerck, Simon L. Lewis, Christelle Gonmadje, Yadvinder Malhi, Jean-Remy Makana, Wannes Hubau, Terry Sunderland, Nils Bourland, Marie-Noël Djuikouo Kamdem, Jacques Mukinzi, Oliver L. Phillips, Martin Gilpin, Bonaventure Sonké, Connie J. Clark, Faustin M. Mbayu, Olivier J. Hardy, Ted R. Feldpausch, Serge K. Begne, Martin J. P. Sullivan, Mélissa Rousseau, Gabriela Lopez-Gonzalez, Eric Chezeaux, Hermann Taedoumg, Corneille E. N. Ewango, and Laurent Nsenga

Subjects
0106 biological sciences, 0301 basic medicine, Carbon Sequestration, Time Factors, chemistry.chemical_element, Plant Science, Carbon sequestration, Forests, 01 natural sciences, Ecology and Environment, Carbon cycle, Carbon Cycle, Trees, 03 medical and health sciences, Tropical climate, Forest ecology, Tropical Climate, Ecology, Carbon sink, Understory, Carbon, 030104 developmental biology, chemistry, Democratic Republic of the Congo, Environmental science, Biologie, 010606 plant biology & botany, Tropical rainforest
Abstract

Quantifying carbon dynamics in forests is critical for understanding their role in long-term climate regulation 1–4 .Yet little is known about tree longevity in tropical forests 3,5–8 ,a factor that is vital for estimating carbon persistence 3,4 .Here we calculate mean carbon age (the period that carbon is fixed in trees 7 ) in different strata of African tropical forests using (1) growth-ring records with a unique timestamp accurately demarcating 66 years of growth in one site and (2) measurements of diameter increments from the African Tropical Rainforest Observation Network (23 sites). We find that in spite of their much smaller size, in understory trees mean carbon age (74 years) is greater than in sub-canopy (54 years) and canopy (57 years) trees and similar to carbon age in emergent trees (66 years). The remarkable carbon longevity in the understory results from slow and aperiodic growth as an adaptation to limited resource availability 9–11 .Our analysis also reveals that while the understory represents a small share (11%) of the carbon stock 12,13 ,it contributes disproportionally to the forest carbon sink (20%). We conclude that accounting for the diversity of carbon age and carbon sequestration among different forest strata is critical for effective conservation management 14–16 and for accurate modelling of carbon cycling 4 .© 2019, The Author(s), under exclusive licence to Springer Nature Limited., SCOPUS: le.j, info:eu-repo/semantics/published

Published
2018

3. Diversity and carbon storage across the tropical forest biome

Author

Connie J. Clark, Kofi Affum-Baffoe, Lan Qie, Timothy R. Baker, Abel Monteagudo-Mendoza, Lise Zemagho, Yadvinder Malhi, Javier Silva Espejo, Patricia Alvarez-Loayza, Lindsay F. Banin, Jefferson S. Hall, Ima Célia Guimarães Vieira, H. Priyadi, Jérôme Chave, Fernando Cornejo Valverde, Peter M. Umunay, J. W. Ferry Slik, Martin Gilpin, Ana Andrade, Andrew R. Marshall, Alvaro Cogollo Pacheco, Bonaventure Sonké, Rodrigo Sierra, Jan Bogaert, Emanuel Gloor, Christopher Baraloto, Guido Pardo, Nicholas J. Berry, Simon L. Lewis, Georgia Pickavance, Axel Dalberg Poulsen, Ismayadi Samsoedin, Vincent A. Vos, Carlos Cerón, Jean-Louis Doucet, Peter S. Ashton, William F. Laurance, Wannes Hubau, Thomas E. Lovejoy, Eric Chezeaux, Zorayda Restrepo, Aida Cuni-Sanchez, Kanehiro Kitayama, Everton Cristo de Almeida, Luiz E. O. C. Aragão, Sophie Fauset, Nadir Pallqui Camacho, Jan Reitsma, Corneille E. N. Ewango, Percy Núñez Vargas, Hans ter Steege, John Terborgh, Roel J. W. Brienen, Jean-François Bastin, Kamariah Abu Salim, Jon C. Lovett, Beatriz Schwantes Marimon, Simon Willcock, Marisol Toledo, Ben Hur Marimon Junior, Serge K. Begne, Greta C. Dargie, Carlos A. Quesada, Terese B. Hart, Martin J. P. Sullivan, Terry Sunderland, Ted R. Feldpausch, Eurídice N. Honorio Coronado, Stuart J. Davies, Lera Miles, Sean C. Thomas, Lip Khoon Kho, Lisa Steel, Jaques Mukinzi, Marie Noel Djuikouo K., Rafael de Paiva Salomão, Terry L. Erwin, Ervan Rutishauser, Edmar Almeida de Oliveira, Rafael Herrera, Shin-ichiro Aiba, Faustin Mpanya Lukasu, Damien Bonal, Sylvester Tan, Esteban Alvarez Dávila, Marielos Peña-Claros, José Luís Camargo, Lee J. T. White, James A. Comiskey, Hermann Taedoumg, Maxime Réjou-Méchain, Pascal Petronelli, Jean-Remy Makana, Ophelia Wang, Richard B. Primack, Gerardo A. Aymard C, Charles De Cannière, Luis Valenzuela Gamarra, Gabriela Lopez-Gonzalez, Leandro Maracahipes, Kuswata Kartawinata, Michael Balinga, Victor Chama Moscoso, Susan G. Laurance, Marcos Silveira, David Harris, Miguel E. Leal, Paulo S. Morandi, John Tshibamba Mukendi, Frans Bongers, Joey Talbot, Douglas Sheil, Reuben Nilus, John R. Poulsen, Oliver L. Phillips, Sch Geog, University of Nottingham, Dept Geog, University College of London [London] (UCL), Plant Systemat & Ecol Lab, Université de Yaoundé, Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Centre National de la Recherche Scientifique (CNRS), Instituto Nacional de Pesquisas da Amazônia (INPA), United Nations Environment Programme World Conservation Monitoring Centre, Missouri Botanical Garden (USA), Universidad Nacional San Antonio Abad del Cusco, Center for International Forestry Research (CIFOR), Coll Marine & Environm Sci, James Cook University, Leiden University, Agence Nationale des Parcs Nationaux du Gabon, Ecole de Terrain en Ecologie Tropicale (ECOTROP), Mensurat Unit, Forestry Research Institute of Ghana, Grad Sch Sci & Engn, Kagoshima University, Inst Biodiversidade & Floresta, Universidade Federal do Oeste do Pará, Universidade Federal do Mato Grosso (UFMT), Ctr Trop Conservat, Duke University [Durham], Universidad Nacional de Colombia, Coll Life & Environm Sci, University of Exeter, Dept Organism & Evolutionary Biol, Harvard University [Cambridge], Programa Ciencias Agro & Mar, Herbario Universitario PORT, Ctr Ecol & Hydrol, Dept Biol Sci, Int Ctr Trop Bot, Florida International University (FIU), Botanique et Modélisation de l'Architecture des Plantes et des Végétations (UMR AMAP), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Biens et services des écosystèmes forestiers tropicaux : l'enjeu du changement global (Cirad-Es-UPR 105 BSEF), Département Environnements et Sociétés (Cirad-ES), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad), Sch Geosci, University of Edinburgh, Biodivers & Landscape Unit, Université de Liège, Gembloux Agro-Bio Tech [Gembloux], Ecologie et Ecophysiologie Forestières [devient SILVA en 2018] (EEF), Institut National de la Recherche Agronomique (INRA)-Université de Lorraine (UL), Forest Ecol & Forest Management Grp, Wageningen University and Research Centre [Wageningen] (WUR), Projeto Dinam Biol Fragmentos Florestais, Herbario Alfredo Paredes, Universidad Agraria del Ecuador, Rougier Gabon, Nicholas Sch Environm, Duke University, Jardín Botánico de Medellín, Inventory & Monitoring Program, National Park Service, Smithsonian Institution, Andes to Amazon Biodiversity Program, Instituto de Investigaciones de la Amazonía Peruana, Smithsonian Tropical Research Institute, Landscape Ecol & Vegetal Prod Syst Unit, Université Libre de Bruxelles [Bruxelles] (ULB), Dept Bot & Plant Physiol, Fac Sci, University of Buea, Wildlife Conservation Society, Centre de Formation et de Recherche en Conservation Forestière (CEFRECOF), Department of Biology [Copenhagen], Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), Ctr Ecol, Instituto Venezolano de Investigaciones Cientificas (IVIC), Inst Geog & Reg Forsch, University of Vienna, Royal Botanic Garden Edinburgh, Lukuru Wildlife Res Fdn, Div Vertebrate Zool, National Museum of Natural History, Herbarium Bogoriense, Indonesian Institute of Sciences, Integrat Res Ctr, Field Museum of Natural History [Chicago, USA], Trop Peat Res Inst, Biol Res Div, Malaysian Palm Oil Board, Kyoto University, Ctr Trop Environm & Sustainabil Sci, Coll Sci & Engn, Dept Environm Sci & Policy, George Mason University, Fac Sci Agron, University of Kisangani, Sch Geog & Environm, University of Oxford, Universidade Federal de Goiás [Goiânia] (UFG), Flamingo Land LTD, Dept Environm, CIRCLE, University of York, Salonga Natl Pk, sabah Parks, Universidad Autonoma del Beni, Inst Boliviano Invest Forestal, Ecologie des forêts de Guyane (UMR ECOFOG), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-AgroParisTech-Université de Guyane (UG)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Natural History Museum [Oslo], University of Oslo (UiO), Southern Swedish Forest Res Ctr, Swedish University of Agricultural Sciences (SLU), Bur Waarderburg, Fundación Con-Vida, CarboForExpert, Fac Sci, Environm & Life Sci, University of Brunei Darussalam (Biology Department), Museu Paraense Emílio Goeldi, Forestry Research and Development Agency (FORDA), Norwegian University of Life Sciences (NMBU), Geoinformática y Sistemas , Cia. Ltda (GeoIS), Museu Univ, Universidade Federal do Acre (UFAC), World Wide Fund for Nature, CTFS AA Asia Program, Fac Forestry, University Stefan cel Mare of Suceava (USU), Sch Forestry & Environm Studies, Yale University [New Haven], Centro de Investigación y Promoción del Campesinado Norte Amazónico, Sch Earth Sci & Environm Sustainabil, Northern Arizona University [Flagstaff], Biol Sci, Liverpool John Moore University (ljmu), Sch Environm Nat Resources & Geog, Bangor University, European Research Council (ERC), Gordon and Betty Moore Foundation, David and Lucile Packard Foundation, European Union's Seventh Framework Programme 283080, 282664, Natural Environment Research Council (NERC) Urgency Grants, NERC Consortium Grant 'AMAZONICA' NE/F005806/1, NERC Consortium Grant 'TROBIT' NE/D005590/1, NERC Consortium Grant 'BIO-RED' NE/N012542/1, NERC New Investigators Grant, Royal Society, Centre for International Forestry (CIFOR), Gabon's National Parks Agency (ANPN), NERC PhD Studentship, UNEP-WCMC, NERC research fellowship NE/I021160/1, Royal Society University Research Fellowship ERC Advanced Grant (T-FORCES), Phillip Leverhulme Prize, Royal Society Wolfson Research Merit Award, NERC studentship, RGS-IBG Henrietta Hutton Grant, National Council for Science and Technology Development of Brazil (CNPq) PELD/403725/2012-7, CNPq/PPBio/457602/2012-0, National Council for Science and Technology Development of Brazil (CNPq) Productivity Grant, Leverhulme Trust under the Valuing the Arc project, Missouri Botanical Garden, Sullivan, Martin J. P., Université de Yaoundé I, Universidad Nacional de San Antonio Abad del Cusco (UNSAAC), Consultative Group on International Agricultural Research [CGIAR] (CGIAR), Florida International University [Miami] (FIU), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD [France-Sud]), Biens et services des écosystèmes forestiers tropicaux : l'enjeu du changement global (UPR BSEF), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad), Wageningen University and Research [Wageningen] (WUR), Instituto de Investigaciones de la Amazonía Peruana (IIAP), Université libre de Bruxelles (ULB), University of Vienna [Vienna], Indonesian Institute of Sciences (LIPI), University of Oxford [Oxford], Université des Antilles (UA)-Université de Guyane (UG)-Centre National de la Recherche Scientifique (CNRS)-AgroParisTech-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA), Southern Swedish Forest Research Centre, Museu Paraense Emílio Goeldi [Belém, Brésil] (MPEG), Université de Toulouse (UT), James Cook University (JCU), Universiteit Leiden, Agence Nationale des Parcs Nationaux du Gabon (ANPN), Harvard University, University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH), and Royal Botanic Garden [Edinburgh]

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, INCREASES, ALPHA-DIVERSITY, [SDV]Life Sciences [q-bio], Biome, Biodiversity, COMPLEMENTARITY, forêt tropicale, Forests, 01 natural sciences, AMAZONIAN FORESTS, Tropic Climate, biodiversité, biomasse aérienne des arbres, conservation des forêts, Tropical climate, stockage du carbone, Biomass (ecology), Multidisciplinary, PRODUCTIVITY, Agroforestry, Ecology, Plants, PE&RC, Classification, Tropical ecology, Chemistry, séquestration du carbone, biome, diversité variétale, protection de la forêt, P01 - Conservation de la nature et ressources foncières, ABOVEGROUND BIOMASS, tropical forest, Asia, F60 - Physiologie et biochimie végétale, TREE ALPHA-DIVERSITY, forêt amazonienne, CONSERVATION, 010603 evolutionary biology, Article, Ecology and Environment, Phénomènes atmosphériques, Forest ecology, Life Science, Bosecologie en Bosbeheer, Forest, AFRICAN RAIN-FORESTS, WOOD PRODUCTION, BIODIVERSITY, CLIMATE, K70 - Dégâts causés aux forêts et leur protection, atténuation des effets du changement climatique, 0105 earth and related environmental sciences, Tropical Climate, Western Hemisphere, TREE SPECIES RICHNESS, Tropics, Plant, 15. Life on land, Forest Ecology and Forest Management, Carbon, biodiversité forestière, DOMINANCE, 13. Climate action, Earth and Environmental Sciences, Africa, Alpha diversity, Americas, structure de la canopée
Abstract

Tropical forests are global centres of biodiversity and carbon storage. Many tropical countries aspire to protect forest to fulfil biodiversity and climate mitigation policy targets, but the conservation strategies needed to achieve these two functions depend critically on the tropical forest tree diversity-carbon storage relationship. Assessing this relationship is challenging due to the scarcity of inventories where carbon stocks in aboveground biomass and species identifications have been simultaneously and robustly quantified. Here, we compile a unique pan-Tropical dataset of 360 plots located in structurally intact old-growth closed-canopy forest, surveyed using standardised methods, allowing a multi-scale evaluation of diversity-carbon relationships in tropical forests. Diversity-carbon relationships among all plots at 1 ha scale across the tropics are absent, and within continents are either weak (Asia) or absent (Amazonia, Africa). A weak positive relationship is detectable within 1 ha plots, indicating that diversity effects in tropical forests may be scale dependent. The absence of clear diversity-carbon relationships at scales relevant to conservation planning means that carbon-centred conservation strategies will inevitably miss many high diversity ecosystems. As tropical forests can have any combination of tree diversity and carbon stocks both require explicit consideration when optimising policies to manage tropical carbon and biodiversity., 0, SCOPUS: ar.j, info:eu-repo/semantics/published

Published
2017

4. A novel class of azatricyclononanes: pentasubstituted cyclopropanes from an uncatalysed reaction

Author

Mark G. Moloney, Martin Gilpin, Lawrence Harris, Andrew R. Cowley, and Amber L. Thompson

Subjects
Inorganic Chemistry, chemistry.chemical_compound, Class (set theory), chemistry, Stereochemistry, Organic Chemistry, Organic chemistry, Stereoselectivity, Pyroglutamic acid, Physical and Theoretical Chemistry, Catalysis
Abstract

The direct and versatile stereoselective synthesis of a novel class of cyclopropyl derivatives of pyroglutamic acid is reported, using substituted diaryldiazo compounds. The course of the reaction has been investigated, and yields of substituted fluorenylcyclopropanes are greater than those of diphenylmethylcyclopropane analogues. © 2009 Elsevier Ltd. All rights reserved.

Published
2016

5. Substituted diaryldiazomethanes and diazofluorenes: Structure, reactivity and stability

Author

Aman Karim, Philip J. Davis, Claire Thompson, Amber L. Thompson, Lawrence Harris, Matthew J. Pound, Mark G. Moloney, and Martin Gilpin

Subjects
nervous system, Chemistry, musculoskeletal, neural, and ocular physiology, Organic Chemistry, Drug Discovery, Molecule, Organic chemistry, Reactivity (chemistry), macromolecular substances, Structure reactivity, Biochemistry, Chemical synthesis
Abstract

The synthesis of several substituted diaryldiazomethanes and diazofluorenes, and an assessment of their structure, reactivity and stability, is reported. © 2011 Elsevier Ltd. All rights reserved.

Published
2016

7. Identification of a Series of Tricyclic Natural Products as Potent Broad-Spectrum Inhibitors of Metallo-β-Lactamases

Author

David G. Tew, Alfonso Rivera-Sagredo, Paloma Perez, Cheryl A. Janson, Nestor O. Concha, Martin Gilpin, Juan A. Hueso-Rodríguez, Michael Rees, John H. Bateson, Jesús Ángel de la Fuente, Helen F. Boyd, Niconovich Nancy, Stewart C. Pearson, Christy Cheever, David J. Payne, E. Diez, and Stephen Rittenhouse

Subjects
Models, Molecular, medicine.drug_class, Klebsiella pneumoniae, Antibiotics, Bacillus, Microbial Sensitivity Tests, Chaetomium, medicine.disease_cause, beta-Lactamases, Microbiology, Bacillus cereus, polycyclic compounds, medicine, Pharmacology (medical), Enzyme Inhibitors, Antibacterial agent, Pharmacology, chemistry.chemical_classification, Binding Sites, biology, Pseudomonas aeruginosa, Drug Synergism, Meropenem, Chemistry, Biosynthesis, biochemical phenomena, metabolism, and nutrition, bacterial infections and mycoses, biology.organism_classification, Kinetics, Infectious Diseases, Enzyme, Biochemistry, chemistry, Enzyme inhibitor, Fermentation, Serratia marcescens, biology.protein, bacteria, Thienamycins, Bacteroides fragilis, beta-Lactamase Inhibitors, Heterocyclic Compounds, 3-Ring
Abstract

Metallo-β-lactamases provide bacteria with an efficient and effective way of mediating resistance to β-lactam-based antibacterial agents. More significantly, they confer resistance to carbapenems. Therefore, if metallo-β-lactamases increase in prevalence, they could compromise the efficacy of this group of antibiotics to treat life-threatening hospital infections. Metallo-β-lactamases have now been identified in a wide spectrum of clinically important pathogens, such as Klebsiella pneumoniae, Pseudomonas aeruginosa, Serratia marcescens, and Acinetobacter sp. (21; H. Ito, K. Senda, T. Yagi, K. Shibayama, M. Ohta, N. Kato, and Y. Arakawa, Abstr. 37th Intersci. Conf. Antimicrob. Agents Chemother., abstr. C-93, 1997). These enzymes also possess a proven capability to disseminate through bacterial populations, which is demonstrated by the spread of the IMP-1 metallo-β-lactamase in Japan (reviewed in reference 17). The spread of this enzyme is thought to be facilitated by its being encoded on an integron (1). More recently, clinical isolates producing metallo-β-lactamases have been identified in Europe (5, 12, 24). One approach to combating this potential clinical problem is the use of a specific metallo-β-lactamase inhibitor in combination with a β-lactam antibiotic. In this regard a range of different non-β-lactam based molecules have been identified as specific inhibitors of these enzymes. A series of mercaptoacetic acid thiol ester compounds were identified as mechanism-based, irreversible inhibitors of metallo-β-lactamases (18). Walter et al. (23) described a series of trifluoromethyl alcohol and ketone inhibitors that were competitive inhibitors of a range of metallo-β-lactamases, and a group of biphenyl tetrazole compounds have been shown to be specific inhibitors of the Bacteroides fragilis CfiA-type metallo-β-lactamase (22). None of these compounds exhibited significant synergy with β-lactam antibiotics, nor did they exhibit potent broad-spectrum inhibition of metallo-β-lactamases. However, a recently discovered series of mercaptocarboxylates have been shown to exhibit both broad-spectrum metallo-β-lactamase inhibitory activity and antibacterial synergy with meropenem (17). In our quest to identify novel inhibitors of metallo-β-lactamases, we screened natural product extracts against the Bacillus cereus II enzyme and identified an extract from a strain of Chaetomium funicola with inhibitory activity against metallo-β-lactamases. SB236050, SB238569, and SB236049 were successfully extracted and purified from this extract, and we now report on the purification, extraction, and characterization of this novel series of metallo-β-lactamase inhibitors derived from a natural product.

Published
2002

8. Isolation and Structure Determination of Two Novel Phenazines from a Streptomyces with Inhibitory Activity against Metallo-enzymes, Including Metallo-.BETA.-lactamase

Author

Martin Gilpin, Mark Fulston, Rebecca Cramp, David J. Payne, and Ian Hood

Subjects
Pharmacology, Molecular Structure, biology, Chemistry, Stereochemistry, Streptomycetaceae, Metalloendopeptidases, Active site, Biological activity, Microbial Sensitivity Tests, biology.organism_classification, Streptomyces, Anti-Bacterial Agents, Structure-Activity Relationship, Fermentation, Drug Discovery, biology.protein, Phenazines, Bacteroides fragilis, Mode of action, Antibacterial activity, Antibacterial agent
Abstract

Two novel metabolites, SB 212021 and SB 212305, have been isolated from a Streptomyces and shown to have molecular formulae of C15H10N2O5 and C20H17N3O8S, respectively. The structures were deduced by a combination of NMR techniques and mass spectral fragmentation patterns and shown to be novel members of the phenazine group of antibiotics. In the absence of added zinc, both compounds had IC50's of 1-75 microM for the Bacteroides fragilis 262 CfiA and Xanthomonas maltophilia L-1 metallo-beta-lactamases. The compounds also inhibited ACE with IC50's of 55 and 68 microM, respectively. Mode of action studies illustrate that the compounds inhibit some metalloenzymes by chelation of the active site metal ion. They exhibit poor antibacterial activity.

Published
1995

11. SB-203207 and SB-203208, two novel isoleucyl tRNA synthetase inhibitors from a Streptomyces sp. II. Structure determination

Author

Catherine S. V. Houge-Frydrych, Peter W. Skett, John W. Tyler, and Martin Gilpin

Subjects
Isoleucine-tRNA Ligase, Magnetic Resonance Spectroscopy, Stereochemistry, Pyridines, Altemicidin, Isoleucine—tRNA ligase, Streptomyces, Hydrolysis, Alkaloids, Drug Discovery, Enzyme Inhibitors, Chromatography, High Pressure Liquid, Antibacterial agent, Pharmacology, chemistry.chemical_classification, Sulfonamides, Antibiotics, Antineoplastic, biology, Molecular Structure, Sulfur Compounds, Streptomycetaceae, biology.organism_classification, Enzyme, chemistry, Indenes, Actinomycetales
Abstract

Two novel isoleucyl tRNA synthetase inhibitors, SB-203207 and SB-203208 have been isolated from a Streptomyces sp. and found to be structurally related to altemicidin. Structures of SB-203207 and SB-203208 have been deduced by a combination of spectroscopic techniques, derivatisation, hydrolysis studies and found to be 4-(aminocarbonyl)-7-[[(2-amino-3-methylpentanoyl)aminosul phonyl]acetamido]-2,4a,5,6,7,7a-hexahydro-6-hydroxy-2-methyl-1H-2- pyrindine-7-carboxylic acid (1) and 4-(aminocarbonyl)-7-[[(2-amino-3-methyl pentanoyl)-aminosulphonyl]acetamido]-2,4a,5,6,7,7a-hexahydro-6-(2- amino-3-phenylbutanoyl oxy)-2-methyl-1H-2-pyrindine-7-carboxylic acid (2), respectively.

Published
2000

12. ChemInform Abstract: TOTAL SYNTHESIS OF β-LACTAMASE INHIBITORS RELATED TO CLAVULANIC ACID

Author

Gerald Brooks, Peter H. Bentley, Martin Gilpin, and Eric Hunt

Subjects
chemistry.chemical_compound, Heptane, β lactamase inhibitor, chemistry, Clavulanic acid, medicine, Total synthesis, Geometric isomer, General Medicine, Medicinal chemistry, Vinyl chloride, medicine.drug
Abstract

(E)-3-Methoxycarbonylmethylene-7-oxo-4-oxa-1-azabicyclo[3.2.0]heptane (6), its geometric isomer (7), and a related vinyl chloride (8) have been obtained by a three-step synthesis from 4-methylthioazetidin-2-one.

Published
1978

13. Total synthesis of β-lactamase inhibitors related to clavulanic acid

Author

Martin Gilpin, Gerald Brooks, Eric Hunt, and Peter H. Bentley

Subjects
chemistry.chemical_compound, Heptane, β lactamase inhibitor, chemistry, Stereochemistry, Clavulanic acid, medicine, Molecular Medicine, Total synthesis, Geometric isomer, Vinyl chloride, medicine.drug
Abstract

(E)-3-Methoxycarbonylmethylene-7-oxo-4-oxa-1-azabicyclo[3.2.0]heptane (6), its geometric isomer (7), and a related vinyl chloride (8) have been obtained by a three-step synthesis from 4-methylthioazetidin-2-one.

Published
1977

14. A new total synthesis of (±)-clavulanic acid

Author

Peter H. Bentley, Martin Gilpin, Eric Hunt, and Gerald Brooks

Subjects
chemistry.chemical_classification, Double bond, Chemistry, Stereochemistry, Clavulanic acid, Organic Chemistry, Drug Discovery, medicine, Total synthesis, Regioselectivity, macromolecular substances, Biochemistry, medicine.drug
Abstract

Regioselective reactions at the terminal double bond of the racemic azetidinone dienylether (4), provides a source of clavulanic acid and several analogues.

Published
1979

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